A gladiator medallion of bronze, which is an alloy known by man since ancient times.

Alloys are basically a mixture of two or more metals. Don't forget that there are many elements on the periodic table. Elements like calcium and potassium are considered metals. Of course, there are also metals like silver and gold. You can also have alloys that include small amounts of non-metallic elements like carbon. Metals are the key thing to remember for alloys.

The main idea with alloys is that they are better at something than any of the metals could be alone. Metallurgists (people who work with metals) sometimes add chromium and/or nickel to steel. While steel is already an alloy that is a very strong metal, the addition of small amounts of the other metals help steel resist rusting. Depending on what element is added, you could create Stainless Steel or Galvanized Steel. It's always about improving specific qualities of the original. Another good example of an alloy happens when metallurgists add carbon to steel. A tiny amount of carbon (a non-metallic element) makes steel stronger. These special carbon-steel alloys are used in armor plating and weapons.

Amalgams are a special type of alloy. Anyway, amalgams are alloys that combine mercury and other metals in the periodic table. You might know mercury as "quicksilver" or the only metal that is liquid at room temperature. The most obvious place you may have seen amalgams is in old dental work. The fillings in the mouths of your grandparents may have been amalgams. We already talked about mercury's being a liquid at room temperature. That physical trait was used when they made fillings. Let's say you have an amalgam of mercury and silver. When it is created, it is very soft. As time passes, the mercury leaves the amalgam and the silver remains. The silver that is left is very hard. Voila! You have a filling!

NOTE: Never, ever, play with mercury! It is very poisonous. You shouldn't even touch it because it will seep into your skin. Dentists don't usually use amalgams with mercury anymore because it may have slowly poisoned people and gotten them sick.

These special colloids (another type of mixture) have a mixture of oils and waters. Think about a botttle of salad dressing. Before you mix it, there are two separate layers of liquids. When you shake the bottle, you create an emulsion. As time passes, the oil and water will separate to their original states.